Dynamoelectric machine coil spacerblock having flow deflecting channel in coil facing surface thereof

ABSTRACT

A dynamoelectric machine includes a rotor having a plurality of adjacent coils; a spaceblock disposed between adjacent coils so as to define first and second cavities adjacent the spaceblock and between mutually adjacent coils; and the spaceblock includes a channel disposed in a coil facing surface of the spaceblock for intercepting and redirecting a circulating coolant flow to the first cavity.

BACKGROUND OF THE INVENTION

The present invention relates to a structure for enhanced cooling of adynamoelectric machine rotor by intercepting and redirecting acirculating coolant flow to an adjacent cavity.

Large dynamoelectric machines, such as a turbo-generator, the rotorconsists of machined slots along its length in which copper coils areplaced. The portions of these coils which extend outside the rotor bodyare called endwindings. In the endwinding region of a rotor, coils areheld tightly by spaceblocks, which are further classified as space,spacer and wedge blocks, depending on their location.

The power output rating of dynamoelectric machines is often limited bythe ability to provide additional current through the rotor fieldwinding because of temperature limitations imposed on the electricalconductor insulation. Therefore, effective cooling of the rotor windingcontributes directly to the output capability of the machine. This isespecially true of the rotor endwindings, where direct, forced coolingis difficult and expensive due to the typical construction of thesemachines. As prevailing market trends require higher efficiency andhigher reliability in lower cost, higher-power density generators,cooling the rotor endwindings becomes a limiting factor. In order tocool the endwindings and coils, a circulating coolant flow is passedthrough the cavities between spaceblocks and coils, and enters thegrooves in coils, which start from these cavities and discharge into achimney.

BRIEF DESCRIPTION OF THE INVENTION

A first aspect of the disclosure provides a dynamoelectric machine,comprising: a rotor having a plurality of adjacent coils; a spaceblockdisposed between adjacent coils so as to define at least a first cavityadjacent the spaceblock and between mutually adjacent coils; and whereinthe spaceblock includes a channel disposed in a coil facing surface ofthe spaceblock for intercepting and redirecting a circulating coolantflow to the first cavity.

A second aspect of the disclosure provides a gas-cooled dynamoelectricmachine, comprising: a rotor having a spindle and a body portion; arotor winding including a plurality of adjacent coils, the plurality ofadjacent coils including axially extending coils disposed on the bodyportion and end straps extending axially beyond at least one end of thebody portion, the coils and the spindle defining an annular regiontherebetween; a plurality of spaceblocks located between adjacent onesof the coils to thereby define first and second cavities, each cavityopen to the annular region and bounded by adjacent spaceblocks andadjacent coils; and wherein each spaceblock includes a channel disposedin a coil facing surface of the spaceblock for intercepting andredirecting a circulating coolant flow to the first cavity.

A third aspect is directed to a spaceblock for a gas-cooleddynamoelectric machine, the spaceblock comprising: a block member formounting between adjacent coils of a rotor winding of the gas-cooleddynamoelectric machine to thereby define first and second cavitiesadjacent to the block member; and a channel disposed in a coil facingsurface of the block member for intercepting and redirecting acirculating coolant flow to the first cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of the endwindings of adynamoelectric machine rotor with stator in opposed facing relationthereto.

FIG. 2 is a cross-sectional top view of the dynamoelectric machine rotortaken along line 2-2 of FIG. 1.

FIG. 3 is a schematic illustration showing conventional passive gas flowinto and through endwinding cavities.

FIG. 4 is a schematic illustration showing an embodiment of a gas-cooleddynamoelectric machine including a spaceblock according to embodimentsof the invention.

FIGS. 5-10 are enlarged perspective views of embodiments of a spaceblockaccording to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings wherein identical reference numerals denotethe same elements throughout the various views, FIGS. 1 and 2 show arotor 10 for a gas-cooled dynamoelectric machine, which also includes astator 12 surrounding the rotor. The rotor includes a generallycylindrical body portion 14 centrally disposed on a rotor spindle 16 andhaving axially opposing end faces, of which a portion 18 of one end faceis shown in FIG. 1. The body portion is provided with a plurality ofcircumferentially-spaced, axially extending slots 20 for receivingconcentrically arranged coils 22, which make up the rotor winding. Forclarity, only five rotor coils are shown, although several more arecommonly used in practice.

Specifically, a number of conductor bars 24 constituting a portion ofthe rotor winding are stacked in each one of the slots. Adjacentconductor bars 24 are separated by layers of electrical insulation 25.The stacked conductor bars are typically maintained in the slots bywedges 26 (FIG. 1) and are made of a conductive material such as copper.Conductor bars 24 are interconnected at each opposing end of the bodyportion by end turns 27 of the coils, in an area which may be referredto as the end strap region. Coils 22 include a coil side sectionincluding axially extending coils 23 and extend axially beyond the endfaces to the end strap region. Collectively, axially extending coils 23and end turns 27 are referred to as endwindings 28. The end turns 27 arealso separated by layers of electrical insulation.

Referring specifically to FIG. 1, a retaining ring 30 is disposed aroundthe end turns at each end of the body portion to hold endwindings 28 inplace against centrifugal forces. Retaining ring 30 is fixed at one endto the body portion and extends out over rotor spindle 16. A centeringring 32 is attached to the distal end of retaining ring 30. It should benoted that retaining ring 30 and centering ring 32 can be mounted inother ways, as is known in the art. The inner peripheral edge ofcentering ring 32 is radially spaced from rotor spindle 16 so as to forma gas inlet passage 34, and endwindings 28 are spaced from rotor spindle16 so as to define an annular region 36. A number of axial coolingchannels 38 formed along slots 20 (FIG. 2) are provided in fluidcommunication with the gas inlet passage 34 via the annular region 36 todeliver cooling gas to the coils 22 (FIG. 2).

Turning to FIG. 2, end turns 27 at each end of rotor 10 (FIG. 1) may becircumferentially and axially separated by a number of spacers orspaceblocks 40. (For clarity of illustration, the spaceblocks are notshown in FIG. 1). Where spaceblocks 40 are disposed between end turns27, they may be referred to as an end strap block 48. Furthermore,axially extending coils 23 may be circumferentially separated by anumber of spaceblocks 40. In this location, spaceblocks 40 may bereferred to as coil side blocks 50 or body wedge blocks 52. The term“wedge” may be applied to these blocks because they may be provided witha wedge shape to accommodate the arcuate shape required to mate withcoils 23 in this location. In any event, spaceblocks 40 are elongatedblock members of an insulating material located in the spaces betweenadjacent coils whether at the axially extending coil side section or endstrap region. Spaceblocks 40 may extend beyond the full radial depth ofthe endstrap section or the coil side section into annular gap 36.

As shown best in FIG. 4, in most cases, a spaceblock 140 disposedbetween adjacent coils (whether axially extending coils 23 or end straps27) defines first and second cavities 160, 162, respectively, adjacentto spaceblock 140 and between mutually adjacent coils. The spacesbetween the concentric stacks of endwindings 28 (FIG. 3) are dividedinto cavities 42. These cavities are bounded on the top by retainingring 30 and on four sides by adjacent end straps 27 and adjacentspaceblocks 48, as shown in FIG. 2. Similarly, as shown best in FIG. 2,spaceblocks 40 between radial stacks of axially extending coils 23 maybe divided into cavities 54, 56. Typically, as shown for the outermostcoils in FIG. 2, spaceblock 40 (body wedge blocks 52) disposed betweenadjacent coils 23 define only one cavity 54 adjacent thereto because thespaceblock is disposed directly against an end of a rotor tooth 29.Cavities 54 are bounded on the top by retaining ring 30 and on foursides by adjacent coils 23 and adjacent spaceblocks 40 (coil side block50 and body wedge block 52). In accordance with embodiments of theinvention, however, as shown for the innermost coils in FIG. 2, cavities56 may also be present where spaceblock 40 (body wedge block 52) is notagainst an end of rotor tooth 29. Cavities 56 may be bounded on the topby retaining ring 30 (or wedges 26 (FIG. 1)) and on four sides byadjacent coils 23, adjacent spaceblocks 40 (coil space blocks 50) and anend of rotor tooth 29. FIG. 1 shows this latter situation.

As best seen in FIG. 1, each of the above-described cavities is in fluidcommunication with gas inlet passage 34 via annular region 36. A portionof the cooling gas entering annular region 36 between endwindings 28 androtor spindle 16 through gas inlet passage 34 thus enters the cavities42, 54, 56, circulates therein, and then returns to annular region 36between the endwinding and the rotor spindle. Gas flow is shown by thearrows in FIGS. 1, 3 and 4. Depending on the direction of coolant flow,any of cavities 42, 54 and 56 may constitute the first cavity 160 orsecond cavity 162.

The inherent pumping action and rotational forces acting in a rotatinggenerator cavity typically produce a large single flow circulation cell,as schematically shown in FIG. 3. This flow circulation cell exhibitsits highest velocity near the peripheral edges of the cavity, leavingthe center region inadequately cooled due to the inherently low velocityin the center region of the cavity. As can be seen from FIG. 3, largeareas of the corner regions are also inadequately cooled because thecircular motion of the flow cell does not carry cooling flow into thecorners.

Referring now to FIG. 4, according to embodiments of the invention, atleast one and preferably each spaceblock 140 includes a channel 144disposed in a coil facing surface 146 of the spaceblock for interceptingand redirecting a circulating coolant flow to a first cavity adjacentthereto. In FIG. 4, spaceblocks 140 are illustrated in a partial sectionof the rotor endwinding assembly in the setting of cavities 42, i.e.,end straps 27. Similarly, spaceblock 140 may be disposed within axiallyextending coils 23 as shown in FIG. 2. Thus, spaceblock 140 may bedisposed within axially extending coils 23 and/or end straps 27, asshown best in FIGS. 1-2. Consequently, as used herein, “coil facing” maymean facing axially extending coils 23 or end straps 27, collectivelycoils 22 of endwindings 28. Channel 144 presents a trough or trench opento coils 23 or end straps 27 through which circulating coolant flow canpass from one location to first cavity 160, thus improving coolant flowbetween cavities, and also providing direct convection cooling of asurface of axially extending coils 23 or end straps 27.

FIGS. 5-10 show enlarged perspective views of different embodiments ofspaceblock 140, and in particular, different channels 140 that may beemployed. Gas flow is shown by the arrows in FIGS. 5-10. As shown inFIG. 4 and FIG. 5, in one embodiment, channel 144 may intercept andredirect the circulating coolant flow from a second cavity 162, i.e., acavity on the other side of spaceblock 140 from first cavity 160. FIG. 6illustrates an embodiment in which channel 144 intercepts and redirectsthe circulating coolant flow from first cavity 160, i.e., channel 144takes coolant flow from first cavity 160 and returns it at a differentlocation within the first cavity. This embodiment may find applicabilitywhere spaceblock 140 has only one cavity adjacent thereto. This mayoccur, for example, as shown for the outermost coils in FIG. 2, for bodywedge blocks 52 positioned directly against an end of rotor tooth 29,i.e., where no cavity 56 exists.

FIG. 7 illustrates a channel 144 that intercepts and redirects thecirculating coolant flow from annular region 36 about spindle 16 ofrotor 10. FIGS. 8 and 9 illustrate a channel 144 that in addition totaking coolant flow from annular region 36, also may intercept andredirect the circulating coolant flow from second cavity 162. That is,coolant flow may be taken from both annular region 36 and second cavity162.

FIG. 10 illustrates a channel 144 that intercepts and redirects thecirculating coolant flow from coil 22 (axially extending coil 23 or endstrap 27) that the channel faces. In this embodiment, a pocket 148 maybe disposed in surface 146 of spaceblock 140 which is in fluidcommunication with the channel such that a circulating coolant flow maybe originated from the coil or endwinding. In this case, coil 22 hassufficient spacing between layers to allow for the coolant flow to begenerated.

Although particular embodiments of channel 144 have been illustrated, itis emphasized that channel 144 may take a variety of different shapesnot explicitly illustrated and that embodiments illustrated may becombined to provide a large variety of possible channel structureswithin the scope of the invention.

Returning to FIG. 5, in an alternative embodiment, any of theabove-described spaceblock 140 and channel 144 configurations may alsoemploy a flow deflector structure 170 facing first cavity 160 and/orsecond cavity 162. Although shown in a block format, flow deflectorstructure 170 may take the shape of a structure as described, forexample, in U.S. Pat. No. 6,465,917 or in U.S. patent application Ser.No. 12/431,054, each of which is hereby incorporated by reference. Asdescribed in the reference patent and application, flow deflectorstructure 170 redistributes coolant flow to the center of a respectivecavity to increase the heat transfer coefficient there.

The terms “first,” “second,” and the like, herein do not denote anyorder, quantity, or importance, but rather are used to distinguish oneelement from another, and the terms “a” and “an” herein do not denote alimitation of quantity, but rather denote the presence of at least oneof the referenced item. The modifier “about” used in connection with aquantity is inclusive of the stated value and has the meaning dictatedby the context, (e.g., includes the degree of error associated withmeasurement of the particular quantity). The suffix “(s)” as used hereinis intended to include both the singular and the plural of the term thatit modifies, thereby including one or more of that term (e.g., themetal(s) includes one or more metals). Ranges disclosed herein areinclusive and independently combinable (e.g., ranges of “up to about 25wt %, or, more specifically, about 5 wt % to about 20 wt %”, isinclusive of the endpoints and all intermediate values of the ranges of“about 5 wt % to about 25 wt %,” etc).

While various embodiments are described herein, it will be appreciatedfrom the specification that various combinations of elements, variationsor improvements therein may be made by those skilled in the art, and arewithin the scope of the invention. In addition, many modifications maybe made to adapt a particular situation or material to the teachings ofthe invention without departing from essential scope thereof. Therefore,it is intended that the invention not be limited to the particularembodiment disclosed as the best mode contemplated for carrying out thisinvention, but that the invention will include all embodiments fallingwithin the scope of the appended claims.

What is claimed is:
 1. A dynamoelectric machine, comprising: a rotorhaving a plurality of adjacent coils; an annular region located about aspindle of the rotor and radially inboard of the plurality of adjacentcoils; and a spaceblock disposed between two of the plurality ofadjacent coils so as to define at least a first cavity adjacent thespaceblock and between the two adjacent coils; wherein the spaceblockincludes a fluid opening in the annular region and a channel disposed ina coil facing surface of the spaceblock for intercepting a coolant flowfrom the annular region via the fluid opening and redirecting thecoolant flow at least partially radially to the first cavity, thechannel being tapered from the fluid opening to a second opening in thefirst cavity.
 2. The dynamoelectric machine of claim 1, wherein thechannel intercepts and redirects the coolant flow from a first portionof the first cavity into a second portion of the first cavity.
 3. Thedynamoelectric machine of claim 1, wherein the channel furtherintercepts and redirects a second coolant flow from a second cavity, thesecond cavity being adjacent the spaceblock and between mutuallyadjacent coils.
 4. The dynamoelectric machine of claim 1, wherein thechannel intercepts and redirects a portion of the coolant flow proximatethe coil that the channel faces.
 5. The dynamoelectric machine of claim4, further comprising a pocket disposed in the surface of the spaceblockand in fluid communication with the channel.
 6. The dynamoelectricmachine of claim 1, wherein the channel defined by the spaceblock issubstantially trihedral.
 7. The dynamoelectric machine of claim 1,wherein the rotor includes a body portion, and each of the plurality ofcoils includes axially extending coils and end turns defining aplurality of endwindings extending axially beyond at least one end ofthe body portion.
 8. The dynamoelectric machine of claim 1, wherein thechannel has a substantially non-uniform cross-section.
 9. Thedynamoelectric machine of claim 1, further comprising at least one flowdeflector structure disposed radially outboard of the channel on atleast one cavity facing surface of the spaceblock.
 10. A gas-cooleddynamoelectric machine, comprising: a rotor having a spindle and a bodyportion; a rotor winding including a plurality of adjacent coils, theplurality of adjacent coils including axially extending coils disposedon the body portion and end straps extending axially beyond at least oneend of the body portion, the coils and the spindle defining an annularregion therebetween; and a plurality of spaceblocks located in anaxially extending coil side section of the rotor between adjacent setsof the coils to thereby define first and second cavities, each cavityopen to the annular region and bounded by adjacent spaceblocks andadjacent coils; wherein each spaceblock includes a fluid opening in theannular region and a channel disposed in a coil facing surface of thespaceblock for intercepting a coolant flow from the annular region viathe fluid opening and redirecting the coolant flow to the first cavity,the channel being tapered from the fluid opening to a second opening inthe first cavity.
 11. The gas-cooled dynamoelectric machine of claim 10,wherein the channel intercepts and redirects the coolant flow from afirst portion of the first cavity into a second portion of the firstcavity.
 12. The gas-cooled dynamoelectric machine of claim 10, whereinthe channel further intercepts and redirects a second coolant flow fromthe second cavity.
 13. The gas-cooled dynamoelectric machine of claim10, wherein the channel intercepts and redirects a portion of thecoolant flow proximate the coil that the channel faces.
 14. Thegas-cooled dynamoelectric machine of claim 13, further comprising apocket disposed in the surface of the spaceblock and in fluidcommunication with the channel.
 15. The gas-cooled dynamoelectricmachine of claim 10, further comprising at least one flow deflectordisposed radially outboard of the channel on at least one cavity facingsurface of the spaceblock.
 16. The gas-cooled dynamoelectric machine ofclaim 10, wherein the channel has a non-uniform cross-section.
 17. Aspaceblock for a gas-cooled dynamoelectric machine, the spaceblockcomprising: a block member for mounting between adjacent coils of arotor winding of the gas-cooled dynamoelectric machine to thereby definefirst and second cavities adjacent to the block member; and a channeldisposed in a coil facing surface of the block member for intercepting acoolant flow from an annular region located about the rotor winding andredirecting the coolant flow to the first cavity, the channel beingtapered from a first opening in the annular region to a second openingin the first cavity.
 18. The spaceblock of claim 17, wherein the channelfurther intercepts and redirects a second coolant flow into the firstcavity from a second cavity, the second cavity being adjacent thespaceblock.